Please navigate to the Reference node in AOT, right click add reference and browse the location were the Microsoft.Dynamics.AX.DMF.ServiceProxy.DmfEntityProxy dll is located then apply ok then restart the AOS service and check.

Also copy the Microsoft.Dynamics.AX.DMF.ServiceProxy.DmfEntityProxy dll and place into the directory were the error pops up and make sure it is available in both servers(AOS and DB) directories.

Please navigate to the Reference node in AOT, right click add reference and browse the location were the Microsoft.Dynamics.AX.DMF.ServiceProxy.DmfEntityProxy dll is located then apply ok then restart the AOS service and check.

Also copy the Microsoft.Dynamics.AX.DMF.ServiceProxy.DmfEntityProxy dll and place into the directory were the error pops up and make sure it is available in both servers(AOS and DB) directories.